| 1 | /* Internals for openat-like functions. |
| 2 | |
| 3 | Copyright (C) 2005-2006, 2009-2014 Free Software Foundation, Inc. |
| 4 | |
| 5 | This program is free software: you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 3 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | /* written by Jim Meyering */ |
| 19 | |
| 20 | #ifndef _GL_HEADER_OPENAT_PRIV |
| 21 | #define _GL_HEADER_OPENAT_PRIV |
| 22 | |
| 23 | #include <errno.h> |
| 24 | #include <limits.h> |
| 25 | #include <stdlib.h> |
| 26 | |
| 27 | /* Maximum number of bytes that it is safe to allocate as a single |
| 28 | array on the stack, and that is known as a compile-time constant. |
| 29 | The assumption is that we'll touch the array very quickly, or a |
| 30 | temporary very near the array, provoking an out-of-memory trap. On |
| 31 | some operating systems, there is only one guard page for the stack, |
| 32 | and a page size can be as small as 4096 bytes. Subtract 64 in the |
| 33 | hope that this will let the compiler touch a nearby temporary and |
| 34 | provoke a trap. */ |
| 35 | #define SAFER_ALLOCA_MAX (4096 - 64) |
| 36 | |
| 37 | #define SAFER_ALLOCA(m) ((m) < SAFER_ALLOCA_MAX ? (m) : SAFER_ALLOCA_MAX) |
| 38 | |
| 39 | #if defined PATH_MAX |
| 40 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (PATH_MAX) |
| 41 | #elif defined _XOPEN_PATH_MAX |
| 42 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (_XOPEN_PATH_MAX) |
| 43 | #else |
| 44 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (1024) |
| 45 | #endif |
| 46 | |
| 47 | char *openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file); |
| 48 | |
| 49 | /* Trying to access a BUILD_PROC_NAME file will fail on systems without |
| 50 | /proc support, and even on systems *with* ProcFS support. Return |
| 51 | nonzero if the failure may be legitimate, e.g., because /proc is not |
| 52 | readable, or the particular .../fd/N directory is not present. */ |
| 53 | #define EXPECTED_ERRNO(Errno) \ |
| 54 | ((Errno) == ENOTDIR || (Errno) == ENOENT \ |
| 55 | || (Errno) == EPERM || (Errno) == EACCES \ |
| 56 | || (Errno) == ENOSYS /* Solaris 8 */ \ |
| 57 | || (Errno) == EOPNOTSUPP /* FreeBSD */) |
| 58 | |
| 59 | /* Wrapper function shared among linkat and renameat. */ |
| 60 | int at_func2 (int fd1, char const *file1, |
| 61 | int fd2, char const *file2, |
| 62 | int (*func) (char const *file1, char const *file2)); |
| 63 | |
| 64 | #endif /* _GL_HEADER_OPENAT_PRIV */ |